# Colormap with an alpha channel

**URL:** <https://discourse.julialang.org/t/colormap-with-an-alpha-channel/45122>\
**Category:** General Usage\
**Tags:** question, plotting, colors\
**Created:** [August 17, 2020, 5:27pm UTC](https://discourse.julialang.org/t/colormap-with-an-alpha-channel/45122 "2020-08-17T17:27:52Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![lazarusA](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/lazarusa/32/6571_2.png) [@lazarusA](https://discourse.julialang.org/u/lazarusA)\
**Post date:** [August 17, 2020, 5:27pm UTC](https://discourse.julialang.org/t/colormap-with-an-alpha-channel/45122/1 "2020-08-17T17:27:52Z")

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does anyone knows how to get a colormap, i.e. viridis with an alpha channel ? (with transparencies).

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**Author:** ![Mattriks](https://sea2.discourse-cdn.com/julialang/user_avatar/discourse.julialang.org/mattriks/32/351_2.png) [@Mattriks](https://discourse.julialang.org/u/Mattriks)\
**Post date:** [August 19, 2020, 12:46am UTC](https://discourse.julialang.org/t/colormap-with-an-alpha-channel/45122/2 "2020-08-19T00:46:11Z")

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Which plotting package are you using? For Gadfly `color` and `alpha` can be specified e.g.

- [Geom.bar](http://gadflyjl.org/stable/gallery/geometries/#%5BGeom.bar%5D(@ref)-1)
- [Scales](http://gadflyjl.org/stable/gallery/scales/)